1. Field of the Invention
The present invention relates to a stereo image processing technology, and it particularly relates to method and apparatus for producing or displaying stereo images based on parallax images.
2. Description of the Related Art
In recent years, inadequacy of network infrastructure has often been an issue, but in this time of transition toward broadband, it is rather the inadequacy in the kind and number of contents utilizing broadband that is drawing more of our attention. Images have always been the most important means of expression, but most of the attempts so far have been at improving the quality of display or data compression ratio. In contrast, technical attempts at expanding the possibilities of expression itself seem to be falling behind.
Under such circumstances, three-dimensional image display (hereinafter referred to simply as “3D display”) has been studied in various manners and has found practical applications in somewhat limited markets, which include uses in the theater or ones with the help of special display devices. From now on, it is expected that the research and development in this area may further accelerate toward the offering of contents full of realism and presence and the times may come when individual users enjoy 3D display at home.
Also, 3D display is something expected to gain its popularity in the years ahead, and for that reason too, forms of display that could not be imagined from the current display devices are being proposed. For example, a technology has been disclosed whereby a selected partial image of a two-dimensional image is displayed three-dimensionally (See, for example, Reference (1) in the following Related Art List).
3. Related Art List    (1) Japanese Patent Application Laid-Open No. Hei11-39507.
In such a trend, a number of problems to be solved of 3D display have long since been pointed out. For example, it is difficult to use an optimal parallax, which is the cause creating stereoscopic effects. In 3D display, the images are, by their nature, not real projections of three-dimensional projects but are images dislocated by a certain number of pixels for the right and left eyes, so that it is not easy to give a sense of naturalness to the artificially created stereoscopic effect.
Also, too much parallax can cause problems; in fact, certain viewers of 3D images (hereinafter referred to also as “user”) may sometimes complain of a slight uncomfortable feeling. This, of course, is caused by a variety of factors, which may include not only the 3D display itself but also a disagreement between the scene being displayed and the user's surrounding circumstances or sense of reality. However, according to our rule of thumb, such a problem tends to occur due to a too large parallax, that is, when the stereoscopic effect is too strong.
Although what has been described above is matters of human physiology, there are other technical factors that can obstruct the popularization of contents or applications of stereo images. Stereoscopic vision is realized by parallax, and suppose that the parallax is represented by the amount of pixel dislocation between the right and the left image, then there are cases where the same 3D image can be properly viewed stereoscopically or not, due to the differences that exist in hardware which are display apparatuses themselves. If the parallax representing distant views surpasses the distance between the eyes, it is theoretically impossible to realize stereoscopic vision. Today display apparatuses, such as PCs (personal computers), television receivers and portable equipment, come in diverse resolutions and screen sizes. And it is difficult, or without methodology to be more accurate, to prepare optimum contents for 3D display in consideration of such a variety of hardware.
And even if the methodology is given, it would be difficult to expect that ordinary programmers will understand it and use it for the preparation of contents and applications.
The technology disclosed by the above-mentioned literature proposes a technique that may solve the problems as described above. However, in order to popularize 3D display in the future, it is necessary to propose additional techniques, accumulate new technologies and combine them for use in products.